1 Field of the Invention
The present invention generally relates to vacuum pumping systems.
2. Description of the Related Art
Semiconductor wafer processing is generally performed in process chambers having sub-atmospheric pressures. Vacuum pumping systems are commonly utilized to achieve and maintain sub-atmospheric pressures within the processing chambers and are typically remotely located (i.e., outside the clean room) to prevent adverse affects on substrate processing.
Vacuum pumping systems serving a typical process chamber generally have a pumping capacity in the range of 1600 l/min up to 25,000 l/min in order to satisfy the needs of typical substrate processing operations. Vacuum pumping systems of this capacity generally consume up to about 6 kilowatts per hour of electricity. Further, vacuum pumps are typically operated at full speed throughout processing, while pressure is controlled by gas flow, throttle valve and isolation valve actuation. Accordingly, vacuum pumping systems are a significant source of power consumption in semiconductor processing systems, as well as other systems.
As a result, new approaches to reducing power consumption are constantly being explored. Reducing the power consumption is desirable both for reducing the energy associated with maintaining vacuum pressures and for reducing the heat generated and subsequent cooling requirements of the vacuum system, the clean room and the facility. Additionally, conservation of energy is additionally desirable for social, economic and environmental benefits.
One possible approach to conserving power is to utilize variable speed pumps. Typically, variable speed vacuum pumping systems include a motor driver which operates to maintain a selected speed setpoint(s). The speed setpoint(s) is determined according to the desired processing conditions. During operation, the speed of the pump may be changed according to the selected speed setpoints. By controlling the speed of the pump it is possible to slow the motor speed when a higher speed is not needed. However, this manner of speed control requires substantial changes to system software in order to integrate a variable speed pump into existing systems. Making software changes to existing systems is both expensive and time-consuming, and requires tracking a number of different software versions.
Therefore, there is a need for a vacuum pumping system that reduces power consumption.
The present invention generally provides methods, apparatus and articles of manufacture for monitoring operating characteristics of a system comprising a variable speed vacuum pump.
One embodiment provides a method of operating a variable speed pump in a vacuum processing environment comprising a vacuum chamber in fluid communication with the variable speed pump and wherein the variable speed pump is in electrical communication with a power source. The method comprises actuating the variable speed pump; sensing an operating characteristic of the variable speed pump indicative of a gas load on the pump; and in response to determining a predetermined behavior of the sensed operating characteristic, changing a speed of the variable speed pump.
Another embodiment provides a method of monitoring at least one operating characteristic of a variable speed pump in a vacuum processing environment comprising a vacuum chamber in fluid communication with the variable speed pump and wherein the variable speed pump is in electrical communication with a power source. The method comprises actuating the variable speed pump by provision of a power signal to the variable speed pump; monitoring a behavior of the power signal; and determining a change in the gas load by analysis of the monitored power signal.
Another embodiment provides a method of operating a variable speed pump in a vacuum processing environment comprising a vacuum chamber in fluid communication with the variable speed pump and wherein the variable speed pump is in electrical communication with a power source. The method comprises operating the variable speed pump; for an operating speed of the variable speed pump, sensing an operating characteristic of the variable speed pump reflective of a gas load on the pump; and reducing a speed of the variable speed pump when the sensed operating characteristic is indicative of a predetermined gas load characteristic requiring less than the operating speed of the pump.
Yet another embodiment provides a computer readable medium containing a program which, when executed, performs an operation for controlling a variable speed pump in a vacuum processing environment comprising a vacuum chamber in fluid communication with the variable speed pump and wherein the variable speed pump is in electrical communication with a power source. The operation comprises actuating the variable speed pump; sensing an operating characteristic of the variable speed pump indicative of a gas load on the pump; and in response to determining a predetermined behavior of the sensed operating characteristic, changing a speed of the variable speed pump.
Yet another embodiment provides a computer readable medium containing a program which, when executed, performs an operation for monitoring at least one operating characteristic of a variable speed pump in a vacuum processing environment comprising a vacuum chamber in fluid communication with the variable speed pump and wherein the variable speed pump is in electrical communication with a power source. The operation comprising actuating the variable speed pump by provision of a power signal to the variable speed pump; monitoring a behavior of the power signal; and determining a change in the gas load by analysis of the monitored power signal.
Yet another embodiment provides a computer readable medium containing a program which, when executed, performs an operation for operating a variable speed pump in a vacuum processing environment comprising a vacuum chamber in fluid communication with the variable speed pump and wherein the variable speed pump is in electrical communication with a power source. The operation comprises, for an operating speed of the variable speed pump, sensing an operating characteristic of the variable speed pump reflective of a gas load on the pump; and issuing a control signal to reduce a speed of the variable speed pump when the sensed operating characteristic is indicative of a predetermined gas load characteristic requiring less than the operating speed of the pump.
Still another embodiment provides a pump speed controller, comprising: a processor; a sensor interface connected to the processor for receiving sensor input from a sensor configured to collect pump operating data; and a control signal interface connected to the processor for transmitting a control signal to a variable speed vacuum pump; wherein the processor is configured by instructions to perform an operation comprising outputting a control signal instructing the variable speed vacuum pump to change its speed upon receipt, via the sensor interface, of pump operating data indicative of a changing gas load on the variable speed vacuum pump.
Yet another embodiment provides a vacuum pump control system, comprising: a vacuum chamber; a variable speed vacuum pump connected to the vacuum chamber; a power supply in electrical communication with the variable speed vacuum pump; a sensor configured to collect operating characteristic information of the speed controller, wherein the operating characteristic information is reflective of a gas load on the variable speed vacuum pump; and a pump speed controller in communication with the variable speed vacuum pump and the sensor and configured to issue speed control signals to the variable speed pump in response to sensor input from the sensor.